Desertification And Deserts

The world has 5.2 billion hectares of useful dry land for agriculture. About 3,6 billion has suffered erosion and soil degradation. In more than 100 countries, 1 billion of the 6 billion world population is affected by desertification, forcing people to leave their farms for jobs in the cities. Desertification is devouring more than 20,000 square miles of land worldwide every year. Desertification affects 74% of the land in North America. In Africa, more than 2.4 million acres of land (73% of its dry lands) are affected by desertification. 

Source:interestingopics.net